无法在树莓派 yocto 构建中导入 python tty 模块

Question

Description

Error while python tty module.

How to enable this module in yocto build?

Environment

root@raspberrypi3-64:~# uname -a
Linux raspberrypi3-64 5.4.83-v8 #1 SMP PREEMPT Wed Jan 20 09:59:41 UTC 2021 aarch64 GNU/Linux

Log

root@raspberrypi3-64:~# python3
Python 3.9.1 (default, Dec  7 2020, 22:33:43) 
[GCC 10.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import tty
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'tty'
>>> 
root@raspberrypi3-64:~# 

Expected output

The tty module should be imported similar to the following Log from the ubuntu 18.04 host

~$ python3
Python 3.6.9 (default, Oct  8 2020, 12:12:24) 
[GCC 8.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import tty
>>> 
~$ 

Answer 1

The python3 recipe is a bit different than others, so it's not always straightforward to find which packages it builds and their name.

For Python standard libraries, such as tty , logging , 2to3 , datetime , one has to read the python3-manifest.json file used in the python3 recipe, see http://cgit.openembedded.org/openembedded-core/tree/meta/recipes-devtools/python/python3/python3-manifest.json?h=master

There, you can see that tty.py is part of the terminal dictionary. All first level key ( terminal included) in the "root" dictionary will be the suffix for the package that will be created. In terminal case, it'll thus be python3-terminal . Which means if one wants tty module on their target, they should add the python3-terminal to their image recipe.

This specific logic of package splitting the standard libraries of Python was a consequence of Python with all its libraries being outrageously big for embedded systems where usually the set of libraries used can be defined and fixed or updated by hand.